Basics of Conservation Tillage Conservation tillage systems leave at least 30% of the soil surface covered with a plant-residue mulch (remains of the previous crop or a cover crop) after planting. This is achieved using tillage tools that do not invert the soil—chisel plows, disks, field cultivators, etc.—but rather shatter or mix it shallowly. Often, a field can be prepared for planting with only one pass of a tillage tool. Many producers adopt conservation tillage because it saves time and fuel while reducing labor requirements; however, the mulch left on the soil surface also provides significant erosion control.
Drainage because the residue cover associated with no-till reduces evaporation of soil water, eliminating one avenue for removal of excess moisture, drainage improvements may be needed on many soils to obtain the best yields in a notill system. Yields under no-till often are more adversely affected by poor drainage than those under conventional tillage. A combination of tile and surface drainage is ideal on soils requiring drainage; however, any drainage improvements are usually beneficial.
Soil characteristics greatly influence the crop yields obtained using no-till and other forms of conservation tillage. Although it may be possible to produce a good crop using these systems on any field, maximum returns normally are achieved by matching the proper tillage systems to the soil at hand. In general, as soil drainage becomes better, tillage can be reduced further.
Well-drained soils, such as Wooster, Fox, Miamian-Celina and Morley-Glynwood, often become moisture deficient as the growing season progresses. The mulch provided by no-till planting normally conserves some water and maintains infiltration on these soils by reducing crusting. As a result, the yield potentials of such soils are usually higher under no-till than under moldboard plowing. Intermediate tillage, such as chisel-plowing, usually produces yields intermediate between moldboard plowing and no-till.
Somewhat poorly drained soils, such as Blount, Crosby, and Fincastle, can be no-tilled with careful management. These soils produce the best yields under no-till if they are systematically drained and crops are rotated. If drainage is not provided, chisel-plowing may provide the best yields under conservation tillage. If adequate drainage and residue are present, yields produced with conservation tillage should be equal, on average, to those obtained by plowing, though different systems may produce the highest yields in different years. These soils crust severely, and in some cases, use of a carefully managed cover crop may be necessary when planting into soybean stubble to ensure adequate surface protection and infiltration. This latter point is most important during the first few years of no-till on such soils.
Poorly drained soils that respond to subsurface drainage improvements, such as Kokomo, Pewamo, and Hoytville, may be adapted to no-till production. Improved drainage and crop rotation are essential to producing top yields. If drainage and rotation are not used, yields under no-till may be much lower than had the field been plowed. Notill soybeans may be successful if drainage and rotation recommendations are followed and precautions for preventing Phytophthora root rot are taken. Soils such as these are considered to be among the most productive in Ohio when plowed and will produce very high yields under conservation tillage if managed properly.
Wet, poorly drained soils, such as undrained Hoytville, or soils that usually do not respond well to tile, such as Clermont, Mahoning and Paulding, normally are not recommended for no-till because surface residue often creates severe moisture excesses. Ridge planting may offer a more attractive alternative on such soils because the elevated ridge dries more quickly in the spring and may allow for significantly earlier planting, which can raise yield potentials. Crop rotation is a must on these soils to avoid low yields, regardless of the tillage system used.
Compaction Considerations No-till and ridge-planting systems should not be used in fields with zones of significant soil compaction. Although repeated use of no-till in a cash-grain rotation may alleviate a compaction problem, waiting for the effect can take several years. Compaction should be eliminated before initiating no-till. Following a controlled traffic pattern can prevent future compaction problems.
Cover Crops A well-managed cover crop is beneficial in certain no-till situations. One of the goals for using cover crops, is to provide extra residue where little residue is present after harvest. The extra residue improves erosion control and reduces soil crusting, among other benefits.
A cover crop always should be planted after a corn silage harvest on soils prone to erosion and crusting, particularly if a no-till planting is anticipated the next year. The use of a cover crop after corn harvest for grain is of questionable value because the corn stover usually provides residue for erosion and crust control and because of the shorter window for cover crop establishment after corn grain harvest. Cover crops may be needed following a soybean harvest if residue levels are not high enough to provide adequate erosion or crusting control, though the benefit of this practice may vary from field to field and should be evaluated on an individual basis. The need for a cover crop for crusting control should decline after several cycles of a corn-soybean rotation because organic matter builds at the soil surface, which will tend to reduce crusting.
Fall-seeded small grains make good cover crops. In Ohio, rye is the most popular. Rye should be terminated when it is no more than 20 inches tall in the spring, unless one plans to harvest the cover crop for straw or feed prior to planting cash crop. Whenever corn is planted into a grass cover of any kind, the field should be watched carefully for armyworm activity in May and June. Fall-seeded oats (that die over the winter) often are used as an alternative when only a light residue addition is wanted.
For more information regarding implementation and adoption of cover crops, see “Chapter 10. Considerations for Using Cover Crops.”
Planting is a critical operation in conservation tillage. Planter operations should be checked and corrected frequently. Not all planters plant under all conditions when adjusted by the book, and experience is often a better guide.
Evaluate soil and residue conditions carefully before planting. Soil should be slightly moist and crumble when squeezed. Planting in too dry soil may cause penetration problems, too shallow planting, and failure of the seed slot to close. Planting into too wet soil may result in poor seed-soil contact or seed furrows that reopen upon drying. All of these factors may reduce plant stands. Generally, farmers should delay no-till planting until late morning to allow residues moistened by dew to dry. Wet residues may be jammed into the seed slot, causing poor seed-soil contact and germination.
Seeding depth is important. In recent years, too shallow planting has produced poor root system development. Plant corn 1.5 to 2 inches deep and soybeans 3/4 to 1 inch deep. Running the coulter 1/2 to 3/4 inch deeper than the desired seeding depth and then making appropriate adjustments of the seeding mechanism should aid in accomplishing these objectives.
Where to place rows is a continuing question. In general, new rows should be planted where material from old rows, particularly row stumps, would not interfere with depth control. Row middles are subject to compaction by repeated wheel traffic, and planting into them should be avoided if stand establishment or crop development has been a problem in the past.
Fertilization practices for no-till or ridge planting are often similar to those recommended for conventional tillage. In particular, soil testing and plant tissue analysis should guide nutrient management. Some management recommendations for specific nutrients are given below.
- Phosphorus. With corn, row placement of phosphorus generally increases yields at lower soil test levels. At adequate soil test levels, and in almost all cases with soybeans, broadcasting is an acceptable production practice from a yield standpoint; however, row placement of phosphorus is encouraged, even in maintenance programs, as a water quality management practice.
- Potassium. Crop response to row placement of potassium has been more inconsistent than for phosphorus. Farmers using a row fertilizer program can include some potassium; however, in nearly all cases, broadcasting is an acceptable practice. Farmers are encouraged to pay close attention to potassium management in no-till and ridge planting because potassium deficiency occurs more frequently in these systems than in plow-based ones.
- Nitrogen. Nitrogen management for no-till or ridge planted corn can be a critical part of the production program. Surface broadcasting of large quantities of urea and urea-ammonium nitrate solutions should be avoided to prevent the possibility of significant nitrogen loss. Detailed nitrogen management is discussed in OSU Extension bulletin 974 Tri-State Fertilizer Recommendations for Corn, Soybeans, Wheat, and Alfalfa and online at agcrops.osu.edu/fertilityresources.
- LIME. It is important to maintain surface pH levels no lower than 6.0. This can be accomplished by frequently adding small amounts of lime to the soil surface. The lime should be applied in the fall and disked in lightly, if possible, to ensure quicker reaction.
Soil Testing because some nutrients and acidity tend to accumulate at the surface of the soil in no-till fields, the methods used to sample are important. Two separate samples are recommended:
- Zero to 4 inches for soil pH and lime requirements. Generally, other analyses at this depth are not needed.
- 2. Zero to 8 inches for all nutrient requirements. This sample should include the entire zero to 8-inch depth, and the probe should penetrate as closely to 8 inches as possible. Avoid fertilizer bands.
Weed Control specific chemical weed control recommendations can be found in OSU Extension bulletin 789 Ohio, Indiana, Illinois, and Missouri Weed Control Guide at all county Extension offices and online at extensionpubs.osu.edu. Weed control may be the most critical phase of any no-till program. Many farmers notice a shift in weed species as they progress into no-till, most likely an increase in annual grasses and perennial broadleaves. Farmers should watch their fields carefully and modify their herbicide programs as shifts occur.
Most no-till and ridge planting systems require a material that burns down existing vegetation at planting, except for early planted corn where no green vegetation is present. A fairly wide choice of burndown material is available; choice usually is dictated by time of year, stage of weed and crop growth, and weed species present. Careful selection and use of burndown materials help avoid costly cleanup treatments later in the season.
Farmers just beginning in ridge planting should use a complete no-till program for weed control. Over time, many have found that their cultivation practice allows them to modify herbicide programs and reduce rates considerably. The ability to do this is dependent on weed pressure and response of soil to cultivation (whether it crumbles or slabs). Farmers attempting to reduce herbicide rates in ridge systems should do so only on the basis of their own experience, not on the advice of others.